Scientists have done well in scouring the DNA of humans to track our origins to the African continent.
But the ancient origins of an animal that is an honorary member of many human families has remained in doubt: We still don’t know where dogs came from.
A group of scientists who are in the middle of a grand examination of canine fossils and modern DNA proposed Thursday to turn the whole conversation on its head.
Suppose dogs didn’t evolve in one place, they suggested, but two. What if domestication of ancient wolves happened in both Asia and Europe — different wolves, different people?
Laurent Frantz and Greger Larson of Oxford University and an international team of scientists who are all part of a dog domestication project run out of Oxford, made the new argument in a paper published in the journal Science. They make clear that although they think their explanation best suits the available evidence, more evidence is needed to confirm it.
Scientists who were not part of the study agreed on the need for more evidence.
“It’s an intriguing hypothesis,” Adam Boyko, a canine geneticist at Cornell University, said.
John Novembre, a geneticist at the University of Chicago, described the idea as “very provocative”
“It’s a hypothesis,” was as far as Peter Savolainen, a geneticist at the Royal Institute of Technology in Stockholm, would go. Dr. Savolainen has argued strongly, with limited support from other researchers, that dogs originated in East Asia, which, he noted, fits with at least half of the paper’s conclusion.
The notion of a dual origin of dogs is something new for geneticists, but Dr. Larson said archaeologists have long considered the possibility that dogs were domesticated more than once.
Separate domestications have occurred with other animals. Dr. Larson and Keith Dobney of Liverpool University found that wild boars were domesticated twice, once in China and once in Anatolia, part of modern Turkey.
For the new study, Dr. Larson and Dr. Frantz obtained DNA sequences from 59 ancient dogs and a complete genome from a 4,800 year-old-dog fossil found at Newgrange, a well-known archaeological site in County Meath, Ireland. They also analyzed other DNA evidence.
They found a deep split between two groups — modern East Asian dogs and those from the Middle East and Europe.
They calculated mutation rates based on the known age of the Irish dog and considered archaeological evidence of migrations as well.
They said the overall picture could be explained two ways — by dogs originating in East Asia and then migrating west, or by dogs originating in Europe and Asia. They said there was a lack of archaeological evidence for an early, steady spread of dogs from an Eastern origin. And, they said, dog fossils from Europe dating to 15,000 years ago predated known migrations.
So they concluded that dogs most likely originated both in Europe and in Asia. The Asian dogs then migrated with humans to Western Europe and the Middle East.
Although the new explanation may seem to complicate an already tangled discussion, Dr. Larson says it actually clears up confusion by explaining two competing ideas, the western and eastern origins of dogs.
Because of the dog domestication project and other ongoing studies of ancient DNA, this is one scientific dispute that may well be solved.
“It’s really an exciting moment,” said Dr. Savolainen.
We may soon know where dogs come from. But not just yet.